Desuperheater



June 4, 1963 3.923677 Patented June 4, 1963 3,692,677 DESUPERI-EATERPaulsen pence, Baton Rouge, La.; L. B. Dexter and 0. C. Paulsen,CG-BKBQMIOYS of said Faulsen Spence, deceased Filed Feb. 8, 1957, Ser.No. 639,150 4- Claims. (til. 261-46) My invention relates to adesuperheater system and an improved desuperheater.

It is often desirable to desuperheat some superheated steam for use inauxiliaries and the like which will not permit or do not require hightemperature steam.

During high and normal loads, water sprayed through the desuperheaterwill be sufiiciently atomized to be evaporated in the line and effectthe cooling of the superheated steam. During light loads, the amount ofcooling water required is small and it is ditdcult or impossible toself-atomize the same, and it is not properly taken up by thesuperheated steam to cool the same. Therefore for light loads, there isa supply of atomizing steam to the desuperheater and this steam must, ofcourse, be at a pressure higher than the pressure in the superheatedsteam line. I have devised a novel means for obtaining atomizing steamat a pressure higher than that normally prevailing in the superheatedsteam line so that there will always be a suflicient supply ofatornizing steam to the desuperheater for light loads.

My invention also contemplates an improved desuperheater, which may beused in my improved or other system.

It is an object of my invention, therefore, to provide an improveddesuperheating system, which may be employed without the use of thespecial pressure reducing valve.

Another object is to provide a desuperheating system wherein theatomizing steam will be turned on when the load drops to a pretedminedlimit.

Another object is to provide an improved desuperheater.

Still another object is to provide a desuperheater involving means forquite accurately regulating the quantity of water passing into thesuperheated steam line.

It is another object to provide an exceedingly simple desuperheater,involving parts which may be readily assembled and disassembled, and, ingeneral, the object is to provide an improved desuperheater anddesuperheater system.

Other objects and various further features of novelty and invention willbe p ointed out or will occur to those skilled in the art, from areading of the following specification in conjunction with theaccompanying drawings.

In said drawings, which show, for illustrative purposes only, apreferred form of the invention-' FIG. 1 is a diagrammatic view showinga complete desuperheater system illustrative of the invention;

FIG. 2 is an enlarged, central, vertical, longitudinal sectional viewthrough a desuperheater, illustrating the invention;

FIG. 3 is a sectional view, taken substantially in the plane of the line33 of FIG. 2; and

FIG. 4 is a sectional view, taken substantially in the plane of the line44 of FIG. 2.

Briefly stated, in a preferred form of the invention, the systemincludes a desuperheater, in a superheated steam line and provided withcooling Water and atomizing steam inlets. I provide novel means forproviding atomizing steam at a requisite pressure. The steam from theboiler is passed through a superheater and then passes into thesuperheated steam line. The steam in passing through the superheater ofcourse loses some pressure, and the pressure in the superheated steamline is for that reason considerably less than the pressure of the steamentering the superheater. This differential in pressure varies, ofcourse, in accordance with design and conditions of operation, but thatdifierential in pressure would usually be sufiicient to atomize thewater. Therefore, in order to provide atomizing steam at a pressurehigher than the pressure in the superheated steam line and withoutemploying a reducing valve, I take saturated steam from the boiler, orat any point in the steam line ahead of the superheater and conduct thatsaturated steam to the desuperheater. The pressure of this saturatedsteam is then higher than that of the superheated steam by about theamount of the pressure loss occurring through the superheater.Desuperheaters of various kinds may be employed in my system, but Iprefer to employ a novel desuperheater, which may, of course, beemployed in systems other than that heretofore referred to.

In the preferred form, the new desuperheater includes a body having anatomizing steam line connected thereto to provide atomizing steam forthe water discharged by the desuperheater. The cooling water ispreferably fed at a more or less constant rate to the water nozzle, anda return passage is provided from the water nozzle for return water notejected through the water nozzle. Thus, with water supplied at a fairlyconstant rate and withdrawn at a lesser rate, the difference between thewater entering the desuperheater and leaving the desuperheater will beejected through the water nozzle itself. When the disuperheater isworking at normal capacity, the nozzle and connections are such that thewater will be fairly well atomized and thus evaporated by thesuperheated steam in the superheated steam line. However, when the loadfalls to, say, 15% of normal, so little water issues from the waternozzle that it may not be properly atomized, and in that case theatomizing steam is turned on the further atomize the water flowing fromthe water nozzle.

I shall first describe the desuperheater system and thereafter describespecifically the improved desuperheater which may be used in the presentor in other desuperheater systems.

As illustrated, there is a boiler 5, conventionally shown, which isconnected through the saturated steam main 6 a with a superheater 7. Thesaturated steam is superheated in the superheater and is dischargedthrough the discharge line 8, which may lead to the main turbine, andthere may be a branch line 9, which leads to a superheated steam line 10in which the steam is to be desuperheated for use in auxiliaries or thelike requiring steam of a lesser temperature.

The desuperheater 12 is mounted in the superheated steam line 10 and thewater nozzle preferably faces upstream. Cooling water enters thedesuperheater through the cooling water pipe 13 at a fairly constantrate and preferably comes from the boiler feed pump. There is a waterreturn pipe 14 leading from the desuperheater, which serves to withdrawwater vfrom the desuperheater so that only the difference in the waterfed to the desuperheater and withdrawn through the line 14 will bedischarged from the nozzle, as will be later described. Thus, the amountof Water discharged may be accurately governed by controlling the returnwater line 14. When a greater quantity of cooling water is required, itis only necessary to throttle the flow through the return line 14 andthus force more of the water out into the superheated steam line. Whenless cooling water is required, the line 14 is not throttled so much andmore of the water flows back away from the desuperheater, and thus lesswater is discharged into the superheated steam line. The throttling ofthe water line 14 is preferably accomplished by a valve 15, controlledby a diaphragm 16, which is acted on by suitable pressure through theline 17 and inlet pipe 18. A thermostat 19, in the desuperheated normalsteam line It), is connected through a controller 20 so as to vary thepressure in the line 17 in accordance with the temperature of thedesuperheated steam; that is, after it passes the desuperheater. Thus,if the desuperheated steam falls to too low a temperature, it will meanthat less water should be supplied to the desuperheater, and thermostat19 will act through the controller 24 to open the valve 15 and letfurther water escape or return from the desuperheater, and thus lesswill be proiected into the superheated steam line. On the other hand, ifsteam in the superheated steam line is not cooled down to the desiredextent, the thermostat 19 will act as heretofore stated, but oppositely,so as to close or throttle the valve 15, thus causing more water to bedischarged into the superheated steam line 10.

As has been stated heretofore, as long as there is a flow of steam inthe superheated steam line, there will be a normal flow of water throughthe desuperheater 12, and such normal flow will ordinarily be selfatomized and thus be evaporated by the superheated steam so as to coolit ofi. However, when the load falls off to, say, 15 of normal,atomizing steam for the water is required, and this atomizing steammust, of course, be at a higher pressure than the pressure in thesuperheated steam line. Since there is no normal reducing valve in thesuperheated steam line, I take saturated steam from the boiler or fromany line between the boiler and the superheater, such as the line 21,and that line conducts steam to the desuperheater so as to'atomize thesmall amount of water flowing at the lower ratings. The atomizing steamto the desuperheater is turned on automatically when the load drops to apredetermined level, as 15% of normal. This automatic action is broughtabout by an atomizing steam valve 15 actuated by a diaphragm 16connected to the control line 17 to which the diaphragm 16 of thecooling water valve 15 is also connected. Thus when the load in linedrops to say of normal little cooling water is required and the controlmechanism 20 drops the control pressure in the line 17 so as to open thecooling water return valve 15 to reduce the amount of water issuing fromthe Water nozzle. This drop in pressure in the control line 17 alsoaffects the diaphragm 16' to open the atomizing steam valve 15 and thusprovides the necessary atomizing steam to the desuperheater. Duringnormal and high load in the line '10, the pressure in the control line17 is raised to increase the cooling water supply and this rise inpressure in the line 17 will act through the diaphragm 16' to close theatomizing steam valve 15'.

As has been stated above, a considerable amount of pressure is lost inthe superheater so that the saturated steam pressure is usually higherby five pounds or more as a general thing than the superheated steampressure, and that differential is sufficient to atomize the waterpassing through the desuperheater. It will thus be seen that no reducingvalve is necessary in order to get a steam pressure high enough toatomize water in the desuperheater, and therefore the cost of thereducing valve is saved and there is no loss of pressure in thesuperheated steam line. a

As has been indicated, various types of desuperheaters may be employed,but I have devised a novel form of desuperheater which is well fittedfor operation in the system as described or in any other desuperheatersystem. The desuperheater, then, as shown in the drawings, includes abody 25, having a rearwardly extending chamber 26 therein closed at therear and open at the front. This desuperheater has means for conductingcooling water to it and through it, so as to provide the necessarycooling water for desuperheating steam.

In the particular form illustrated, near the end of the chamber 26 is atapered seat opening 27 and a water conducting head 28 has acorresponding seat so that the head fits the chamber and closes the endquite tightly. This water conducting head has a rearwardly extendingtubular portion 29, which may fit within the chamber, as

4 indicated at 39 (FIG. 4) to steady the rear end of the waterconducting head. The rearward extension may be closed as by means of aplug 31, as will be understood. The water conducting head 28 may be heldin place by what may 'be termed a water nozzle plug 32, which isthreaded in the end of the body and which bears annularly, as indicatedat 33, against the face of the water conducting head. Between the waterconducting head 26 and h the plug 32, there is an annular channel 34,which in the form shown is principally in the plug 32. The waterconducting head has a plurality of openings 35 extendingtherethroughland communicating with the annular channel 34. The plug 32has inclined openings 36 therein, which extend into what maybe termed awater chamber 37 in the plug and which has a water nozzle 38. The waterconducting head 32, furthermore, has openings 39 communicating with thewater chamber 37 and the nozzle 38 and opening into the rear tubularextension'29. A water inlet pipe 13 is connected to the body andprefer-ably welded, as indicated at 41. This inlet pipe conducts coolingwater into the chamber 26 in the body and the water passes through theopenings 35 into the annular channel 34, as heretofore described. Awater return pipe 14 is secured by a threaded joint 42 to the tubularextension 29 and serves to return the Water passing through the returnopenings 39. Thus, when water enters through the pipe 13, it enters the:annularchannel 26 and then passes through the openings 35 into thechannel 34. From this channel, the water passes through the inclinedchannels or passages 36, which give thewater a whirling motion, as itenters the water chamber 37 and the outlet nozzle 38. Thus, withconsiderable pressure and a considerable volume flowing through thenozzle, the Water will be automatically self sprayed or coned out so asto be easily taken up and evaporated by the superheated steam.

The quantity of cooling Water, as stated, is controlled by throttlingthe return water through the pipe 14. Thus, when it is desired toincrease the Water flow through the nozzle 38, the pipe 14 is throttledand thus the water in the chamber 37 is forced out of the nozzle insteadof passing through the openings 39 and back into the return pipe 14.When less water is required, the return pipe 14 is throttled less, thatis, opened wider and more of the water which entered through the waterinlet pipe is permitted to return and thus less water will be permittedto escape through the nozzle 38.

In order to provide a steam atomizer for the Water passing through thedesuperheater, I employ a steam nozzle member 43, which may be securedto a flange on the body, as by means of screws 44 or the like. Thisnozzle member 43 has an inturned lip 45, which cooperates with a conedsurface 46 on the desuperheater body, thus forming a nozzle to cone thesteam toward the center and thus certainly to atomize whatever waterpasses through the nozzle 38. Steam enters through the steam pipe 21heretofore described, which pipe is secured as by welding to thesteam-nozzle member 43 as indicated at 47. This steam pipe 21 dischargesinto the annular space 48 between the inside of the nozzlemernber 43 andthe body 25.

It will be seen then that the quantity of water may be accuratelycontrolled by controlling the passage of water through the return pipeand the water will always be sprayed into the superheated steam line byits own whirling and atomizing motion duringnormal supply of Water andby the atomizing steam during low flow.

While the invention has been described in considerable detail and apreferred form illustrated, it is to be understood that various changesmay be made within the scope of the invention .as defined in theappended claims.

"I claim:

1. In a desuperheater, a desuperheater body having a cylindrical chamberopen at one end, a water-conducting head fitting within the end of saidchamber and having a tubular extension extending back into said chamber,the rear portion of said tubular extension being relatively square to besupported within said cylindrical chamber at each corner thereof, awater nozzle plug threaded in the front end of said chamber and holdingsaid water-conducting head in place, said water-conducting head and plughaving a water chamber between them and a water nozzle extendingoutwardly therefrom, said plug and said Waterconducting head having anannular groove between them, said water-conducting head having aplurality of openings communicating said cylindrical chamber with saidgroove, water inlet means to said desuperheater body and outside saidWater-conducting head extension, said plug and Waterconducting headhaving spiral grooves between them communicating with said annulargroove and connecting the latter with said water chamber and nozzle,said Water inlet means being connected to said cylindrical chamber forconducting water through said opening and into said annular groove, saidwater-conducting head having a plurality of circularly spaced apartopenings connecting the interior of said tubular extension with saidwater chamher, .a water return pipe connected to said tubular extension,a steam nozzle member secured to said body about said water nozzle plugand providing an annular chamber about the outside of said body andterminating in a narrow annular steam atomizing space between said bodyand said steam nozzle member, and a steam pipe connected to said steamnozzle member and said annular chamber aforesaid.

2. In a desuperheater system, a main steam line, a desuperheater in saidline, cooling-Water-conducting means for conducting cooling water to anddischarging a fraction of the flow of the same through saiddesuperheater into the main line, said last-defined means including anexhaust connection external of the main line for conducting undischargedliquid cooling water away from said desuperheater and thus determiningthe amount of water discharged at said desuperheater, means including asaturated-steam connecteion for conducting saturated atomizing steam toand spraying the same from said desuperheater into said main line toatomize the cooling water, means for controlling the supply of coolingwater sprayed from the desuperheater and including throttling means insaid exhaust connection, another throttling means for controlling thesupply of saturated atomizing steam to said desuperheater, andcoordinated control means for said respective throttling means tothrottle the supply of atomizing steam to said desuperheater when thequantity of cooling water sprayed from said desuperheater increases,said control means being set to shut ofi said steam when the coolingwater discharge flow exceeds a predetermined limit. 3. In adesuperheater system a source of superheated steam, a source of coolingwater, a source of saturated steam,

a main line connected to said source of superheated steam, cooling meanscoupled to said source of cooling water for discharging part of the flowof cooling Water flowing from said source of cooling water, includingintake means substantially external of said main line connected to saidsource of cooling Water,

flow means coupled to said intake means for discharg ing a part of theflow of said cooling water into said main line and exhaust meanssubstantially external of said main line coupled to said intake anddischarge means for conducting the undischarged part of the flow ofcooling water away from said main line,

atomizing means coupled to said source of saturated steam fordischarging atomized saturated steam into said main line to atomize thecooling water,

first control means coupled to said exhaust means to throttle the flowof undischarged cooling water thereby controlling the amount of coolingwater discharged into said main line, second control means coupledbetween said atomizing means and said source of saturated steam tothrottle the flow of saturated steam to said atomizing means,

and coordinating control means coupled to said first and second controlmeans and responsive to the temperature of said superheated steamflowing in said main line at a position downstream of said cooling andatomizing means to throttle the flow of saturated steam when thethrottling of said first control means increases,

said coordinating control means fully throttling said second controlmeans to shut off said saturated steam when said first control means isat a predetermined position, whereby said saturated steam is shut offfrom said main line when the cooling water discharge flow exceeds apredetermined limit.

4. In the desuperheater system of claim 3, said coordinating controlmeans is coupled to said first and second control means by a pressureline and said coordinat ing control means varies the pressure in saidpressure line in response to the said temperature at said downstreamposition.

References Cited in the file of this patent UNITED STATES PATENTS1,582,080 Peabody Apr. 27, 1926 2,155,986 Wheaton Apr. 25, 19392,222,348 Gorrie Nov. 19, 1940 2,276,055 Mastenbrook Mar. 10, 19422,293,314 Spence Aug. 18, 1942 2,373,707 Peabody Apr. 17, 1945 2,550,683Fletcher et a1 May 1, 1951 2,610,837 Puster Sept. 16, 1952 FOREIGNPATENTS 482,901 Great Britain Apr. 7, 1938 649,970 Great Britain Feb. 7,1951

2. IN A DESUPERHEATER SYSTEM, A MAIN STEAM LINE, A DESUPERHEATER IN SAIDLINE, COOLING-WATER-CONDUCTING MEANS FOR CONDUCTING COOLING WATER TO ANDDISCHARGING A FRACTION OF THE FLOW OF THE SAME THROUGH SAIDDESUPERHEATER INTO THE MAIN LINE, SAID LAST-DIFINED MEANS INCLUDING ANEXHAUST CONNECTION EXTERNAL OF THE MAIN LINE FOR CONDUCTING UNDISCHARGEDLIQUID COOLING WATER AWAY FROM SAID DESUPERHEATER AND THUS DETERMININGTHE AMOUNT OF WATER DISCHARGED AT SAID DESUPERHEATER, MEANS INCLUDING ASATURATED-STREAM CONNECTEION FOR CONDUCTING SATURATED ATOMIZING STEAM TOAND SPRAYING THE SAME FROM SAID DESUPERHEATER INTO SAID MAIN LINE TOATOMIZE THE COOLING WATER, MEANS FOR CONTROLLING THE SUPPLY OF COOLINGWATER SPRAYED FROM THE DESUPERHEATER AND INCLUDING THROTTLING MEANS INSAID EXHAUST CONNECTION, ANOTHER THROTTLING MEANS FOR CONTROLLING THESUPPLY OF SATURATED ATOMIZING STEAM TO SAID DESUPERHEATER, ANDCOORDINATED CONTROL MEANS FOR SAID RESPECTIVE THROTTLING MEANS TOTHROTTLE THE SUPPLY ATOMIZING STEAM TO SAID DESUPERHEATER WHEN THEQUANTITY OF COOLING WATER SPRAYED FROM SAID DESUPERHEATER INCREASES,SAID CONTROL MEANS BEING SET TO SHUT OFF SAID STEAM WHEN THE COOLINGWATER DISCHARGE FLOW EXCEEDS A PREDETERMINED LIMIT.